Regionally thinned microstructures for microbolometers

Abstract

Microbolometers with regionally thinned microbridges are produced by depositing a thin film (0.6 μm) of silicon nitride on a silicon substrate, forming microbridges on the substrate, etching the thin film to define windows in a pixel area, thinning the windows, releasing the silicon nitride, depositing a conductive YBaCuO film on the bridges, depositing a conductive film (Au) on the YBaCuO film, and removing selected areas of the YBaCuO and conductive films.

1. A method of producing a microbolometer comprising the steps of:
 (a) depositing a thin film of a compound selected from the group consisting of silicon nitride, silicon dioxide and vanadium oxide on a substrate formed of a material selected from the group consisting of silicon, GeAs, GeLnP, quartz, a metal oxide and a ceramic; 
 (b) forming microbridges on the substrate; 
 (c) defining windows in a pixel area of the microbridges; 
 (d) etching the windows making them thinner than the remainder of the pixel area; 
 (e) releasing the thin film by chemical etching; 
 (f) depositing a thin film of material selected from the group consisting of YBaCuO, a nickel iron alloy, amorphous silicon, germanium, a low temperature superconductor and a high temperature superconductor on the microbridges; 
 (g) depositing a conductive film on the thin film; and 
 (h) removing selected areas of thin and conductive films. 
 
   
   
     2. A method of producing a microbolometer comprising the steps of:
 (a) depositing a thin film of silicon nitride on a silicon substrate; 
 (b) forming microbridges on the substrate; 
 (c) defining windows in a pixel area of the microbridges; 
 (d) etching the windows making them thinner than the remainder of the pixel area; 
 (e) releasing the silicon nitride film by chemical etching; 
 (f) depositing a thin YBaCuO film on the microbridges; 
 (g) depositing a conductive film on the YBaCuO film; and 
 (h) removing selected areas of the YBaCuO and conductive films. 
 
   
   
     3. The method of  claim 2 , wherein the conductive layer is Au. 
   
   
     4. The method of  claim 3 , wherein the microbridges are formed using UV lithography. 
   
   
     5. The method of  claim 4 , wherein the thin film is etched in step (c) using reactive plasma etching. 
   
   
     6. The method of  claim 5 , wherein the reactive plasma etching is carried out in a He/CHF 3 /SF 6  gas mixture. 
   
   
     7. The method of  claim 3 , wherein the YBaCuO and Au are deposited by RF magetron sputtering.